ABSTRACT
Several epidemiological studies conducted on underground miner's show that exposure to elevated levels of radioactive radon gas is expected to increase the risk of lung cancer. Relative risk of lung cancer is almost linear with radon exposure. Elevated concentrations of radon are not only reported within mines but also for closed indoor environment of general public houses. Measurements of radon play a serious role in scrutinizing public health and safety in homes. Indoor radon measurements were taken over a period of year, using CR-39 detectors. Measured indoor radon concentrations, was converted in to excess relative risk [ERR] factors by using the risk model reported in the Biological Effects of Ionizing Radiation [BEIR VI] report. ERR was calculated for age groups of 35 and 55 years. A careful selection of occupancy factor based on interviews with house occupants has been made. Using this local occupancy factor, average excess lung cancer risk for the age group of 35 and 54 y peoples was found to 0.51 +/- 0.03 and 0.42 +/- 0.03. Similarly average values of ERR for local occupancy factor with ages 35 and 55 years was found as 0.59 +/- 0.03 and 0.45 +/- 0.03. The overall average excess lung cancer risk for the studied area was 0.46 +/- 0.03. The study suggested that United State Environmental Protection Agency [US EPA] occupancy factor gave a higher excess lung cancer risk as compared with the local occupancy factor used for studied areas. The ERR due to indoor radon is within the standard limits and does not pose any serious threat to the occupants of the houses under investigation
ABSTRACT
Health hazards associated with exposure due to the natural radioactivity which is a part of our physical environment are of great concern. In order to assess the risks associated with exposure due to the natural radioactivity in soil and building materials, extensive studies have been carried out all over the world. The most commonly encountered radionuclide's are [238]U, [232]Th, their decay products and [40]K. In order to study the concentration of these radionu-clides soil, sand, gravel aggregates, bricks and marble, samples were collected from different sites and local suppliers of the district Mirpur, Azad Kashmir [Pakistan]. [226]Ra, [232]Th, and [40]K activities in the collected samples were measured using HPGe detector. The measured specific radioactivity concentration of [226]Ra, [232]Th and [40]K in the studied samples ranged from 10 +/- 1 to 47 +/- 2, 18 +/- 1 to 75 +/- 4 and 40 +/- 3 to 683 +/- 3 Bq.kg[-1], respectively. From the measured activity concentration, radium equivalent activity, external and internal hazard indices, gamma and alpha indices, terrestrial absorbed dose and annual effective dose were calculated. Maximum value of radium equivalent activity of 197.1 +/- 9 Bq.kg[-1] was observed in soil sample whereas minimum value of 45.9 +/- 2 Bq.kg[-1] was found in gravel aggregates. Relatively higher mean values of hazard indices were found in brick samples. Annual effective dose varied from 0.06 +/- 0.01 to 0.47 +/- 0.02 mSv.y[-1]. Current values of annual effective dose, radium equivalent activity and hazard indices have been found to be within the recommended limits